you get 1 for a single domain and thats it. they can stop doing it at any time, eg after they get everyone's business and services all disallow self sig.ed cert

you get 1 for a single domain and thats it. they can stop doing it at any time, eg after they get everyone's business and services all disallow self sig.ed certs. also by nature these certs are poorly checked and thys less trustable than some other, obviously